In OO-style development, the value null causes endless issues. In FP-style development null is a much smaller problem, because using null isn't ideomatic style. In FP, instead of using null to indicate absence, lists tend to be empty, and optional values tend to use Option (a.k.a Maybe) types.

In one of our C# codebases, which is predominantly OO, using FP-style list processing often runs into the null problem.